There are a few planets in Pikmin 2 and Pikmin 3 that aren't mentioned and are only seen in each game's opening scene, which both show shots of space. They are purely aesthetic, and don't appear or are mentioned anywhere else in the games or series. In Pikmin 3, lots of these planets are nearly identical, but there are still distinguishable "types".
This planet is large, yellow, and has three moons. Hocotate Freight is shown to have delivered supplies to it. The moons are colored green, orange, and blue.
Most of these planets are perfectly rounded, pearly spheres, resembling the gas giants Uranus and Neptune. Others, seen in the Drake's takeoff scene seem to have a more rocky texture. None of these planets have moons.
These planets are rigid and rocky, and might as well be asteroids. This may suggest that they are quite small, as small planets in real life often develop strange shapes because of a lack of gravity.